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From: Jeff Law <>
Subject: Re: [PATCH] PR tree-optimization/109417 - Check if dependency is valid before using in may_recompute_p.
Date: Wed, 5 Apr 2023 15:52:36 -0600	[thread overview]
Message-ID: <> (raw)
In-Reply-To: <>

On 4/5/23 14:10, Andrew MacLeod via Gcc-patches wrote:
> When a statement is first processed, any SSA_NAMEs that are dependencies 
> are cached for quick future access.
> if we ;later rewrite the statement (say propagate a constant into it), 
> its possible the ssa-name in this cache is no longer active.   Normally 
> this is not a problem, but the changed to may_recompute_p forgot to take 
> that into account, and was checking a dependency from the cache that was 
> in the SSA_NAME_FREE_LIST. It thus had no SSA_NAME_DEF_STMT when we were 
> expecting one.
> This patch simply rejects dependencies from consideration if they are in 
> the free list.
> Bootstrapping on x86_64-pc-linux-gnu  and presuming no regressio0ns, OK 
> for trunk?
eek.  So you've got a released name in the cache?  What happens if the 
name gets released, then re-used?  Aren't you going to get bogus results 
in that case?


  reply	other threads:[~2023-04-05 21:52 UTC|newest]

Thread overview: 8+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2023-04-05 20:10 Andrew MacLeod
2023-04-05 21:52 ` Jeff Law [this message]
2023-04-11  9:21   ` Richard Biener
2023-04-24 13:51     ` Andrew MacLeod
2023-04-25  7:17       ` Richard Biener
2023-04-26  2:34       ` Jeff Law
2023-04-26 19:26         ` [COMMITTED 1/5] PR tree-optimization/109417 - Don't save ssa-name pointer in dependency cache Andrew MacLeod
2023-04-06 10:38 ` [PATCH] PR tree-optimization/109417 - Check if dependency is valid before using in may_recompute_p Jakub Jelinek

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